86 740 gle poor milage 12mpg

  • Thread starter Thread starter pepe256
  • Start date Start date
P

pepe256

any suggsetions this is emptying my pockets i have checked for vacumm leaks
and none heard or seen any other things?
 
have similar problem with 87 740gle. it starts to cut out like it is
starving for gas or has dirt in injectors then runs fine for a while then
does it all over again any suggestions to help out is appericiated
 
mine was doing that when i was hitting around 55mph then i had the lines
cleaned and a fuel filter replaced and that fixed it for me
 
pepe256 said:
mine was doing that when i was hitting around 55mph then i had the lines
cleaned and a fuel filter replaced and that fixed it for me
Click to expand...
_____
If in addition to very high fuel consumption the tail pipe is very
black, and smells of fuel, then you should check the oxygen sensor. If
it has failed, the ECU will have been running the engine on a rich
mixture, causing fuel consumption to almost double. Measure the sensor
output voltage as a double check. Generic sensors are available. Is
yours a 1-wire or 2-wire type of sensor ? Probably a 3-wire one. If
you need details about generic sensors, please email me off-line at
c.o.n.t.r.e.x AT s.h.a.w..c.a . You need to be concerned about the
cat converter as well because it can plug eventually when the sensor is
not working properly.

/ JCH
 
it doesnt really put out black smoke i changed the muffler a week ago and
been running it and doesnt really look black so if that isnt the problem
any other suggestions
 
pepe256 said:
any suggsetions this is emptying my pockets i have checked for vacumm
leaks
and none heard or seen any other things?
Click to expand...
A long shot but easy to try - our 85 765T ran very rich at high throttle,
and with the turbo we could see black smoke as we tried to get it to boost.
After driving on the highway the plugs were sooted up. It turned out to be a
bad connection at the cylinder head temperature sensor, located under about
the #3 intake manifold branch. It isn't visible, but if you stick your hand
under there you can feel it. Try pulling the connector off (typical spring
latch, just like the injectors) and pushing it back on. Then clean all the
goo off your forearm.

Mike
 
pepe256 said:
it doesnt really put out black smoke i changed the muffler a week ago and
been running it and doesnt really look black so if that isnt the problem
any other suggestions
Click to expand...

Are you leaking? Is someone stealing your gas? The fuel is going somewhere,
if it's not smoking check the catalytic converter, is it glowing after a
drive? If so things to check would be the coolant temperature sensor that
connects to the ECU and the AMM, either one can cause it to run rich. If
it's running fine and the cat isn't excessively hot then I would suspect a
leak or theft.
 
I do not believe that i am leaking and there is no one stealing my gas and
im not smoking so i dont know im not smelling any leaking gas under the
hood so could it be a temp sensor or what u were saying?
 
mine does it when first starting engine. then after running it at higher
speeds it idles down where it should. could it be the mass air flow
sensor?
 
replaced filter but still having same problem any other sugestions? also
found clogged catylatic convertor put hole in front of it and seems to
help some
 
badboywithbadtoyz said:
replaced filter but still having same problem any other sugestions? also
found clogged catylatic convertor put hole in front of it and seems to
help some
Click to expand...

12 mpg means that it is getting about half what it should, which means
that it is burning twice the fuel it should. This means that WAY too
much fuel is in the cylinders, and you can guarantee that it is
washing lubrication off the rings. Get this taken care of ASAP.

A certified shop can place a bypass pipe in place of the convertor for
testing purposes. Or you could drop the convertor and start it to see
if it runs better- that is, assuming that it is running bad now beyond
the bad fuel mileage.

Replacement convertors are available for about $125 on eBay.

BUT- if the car THINKS it is cold and not warming up it could be
enriching the mixture. Other things could cause that as well I would
think.

If you followed my diatribe on the AMM problem you can see that it
isn't always easy to find out what is wrong. Low spark voltage, bad
AMM, bad IAC valve, carbon tracking in the distributor cap, bad
ignition wires, bad coil, bad electronic ignition ground points, bad
fuel pressure regulator... get the idea? Who knows what it could be?
it took me two weeks to figure out that it was the AMM and only
because I got another one and tried it.

And one last factor that folks sometimes forget... does the car have a
locking gas cap? Remember the story of the guy who was bragging about
the mileage he was getting in his new VW, and the mileage slowly went
up each week to about 48mpg becasue his friends were putting gas in
his car each day? Later he was getting 12mpg when they started taking
the gas OUT!




__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"
 
badboywithbadtoyz said:
replaced filter but still having same problem any other sugestions? also
found clogged catylatic convertor put hole in front of it and seems to
help some
Click to expand...
I had the cat in our 85 765T replaced for less than $150 US parts and labor
maybe ten years ago. It was at an independent shop in Phoenix a friend
recommended.

Isn't there an enormous amount of noise coming from that hole?

Mike
 
You must log in or register to reply here.
Back
Top